The present invention relates generally to a drill guide apparatus for use in removing annular oil seals surrounding a shaft extending from a mechanism, and more particularly, relates to a drill guide apparatus for removing pitman shaft seals from automotive power steering units.
Present-day power steering units have composite resilient seals surrounding the output shaft, or what is more commonly referred to as the pitman shaft. The replacement of these seals can be time consuming and expensive.
One current and somewhat inefficient method of removing the seals involves manually prying the seal assembly from the housing with a pointed tool such as a screw driver. This method often causes damage to one or more steering unit components. This method becomes especially difficult when it is attempted upon a power steering unit mounted on a vehicle.
Another method of removing the seal has been the practice of using a sleeve-like installation tool to drive the seal assembly into the steering housing. The tool is placed against the exposed radial surface of the outer seal and then struck with a hammer to drive the seal assembly into the housing. As in the prior method, damage to shaft, housing and/or shaft bearing may often result.
Tools adapted to extracting annular oil seals surrounding shafts other than pitman shafts have been suggested by prior patents. In particular, puller type tools have been proposed for removing engine crankshaft oil seals. Typically, these tools, as illustrated in U.S. Pat. No. 3,564,696 and 3,909,916, generally employ threaded members to engage the face of the seal in one or more locations and a screw member coacting with the tool and the end of the crankshaft or the housing surface to pull or withdraw the seal from within the housing.
This type of tool is not suitable for removing the oil seals from a power steering unit. Crankshaft oil seals are generally larger in diameter and the crankshaft itself extends only a short distance beyond the surface of the housing. The tools suggested by the prior patents could easily accommodate typical crankshaft and housing dimensions and configurations. In a power steering unit, the pitman shaft generally extends well beyond the housing and more importantly is of a diameter much smaller than that of a crankshaft. Additionally, the pitman shaft seal is a composite seal comprising multiple seals and metal spacing discs whereas the crankshaft seal is generally a single component. It would be difficult if not impossible to engage and extract the components of a power steering seal by a tool constructed in accordance with the prior patents.
Attempts have been made to manually drill out the oil seals, usually with little success. In many cases, misalignment and chattering of the drill precluded the removal of the seal and at times caused damage to one or more steering unit components.